Conserved sequence motifs upstream from the co-ordinately expressed vitellogenin and apo VLDLII genes of chicken

The vitellogenin and apoVLDLII yolk protein genes of chicken are transcribed 1n the liver upon estrogenization. To get Information on putative regulatory elements, we compared more than 2 kb of their 5′ flanking DMA sequences. Common sequence motifs were found 1n regions, exhibiting estrogen-induced changes in chromatin structure. Stretches of alternating pyrinidines and purines of about 30-nucleotides long are present at roughly similar positions. A distinct box of sequence homology in the chicken genes also appears to be present at a similar position 1n front of the vitellogenin genes of Xenopus laevis, but 1s absent from the estrogen-responsive egg-white protein genes expressed in the oviduct. In front of the vitellogenin (position −595) and the VLDLII gene (position −548), a DNA element of about 300 base-pairs was found, which possesses structural characteristics of a mobile genetic element and bears homology to the transposon-like Vi element of Xenopus laevis.